Hi Chris, On Fri, 13 Jul 2007 11:03:11 +0530, Chris Albertson <[EMAIL PROTECTED]> wrote:
> > How long did it take for the message to get from the guts of the > GPS to your terminal? And is it always the same amount of time? > The message does not get to you at the exact "turn of the second" > > The GPS does not tell you the time it is now. It tells you the > time it was when it formatted the message. > > The clock will be slow by some number of milliseconds. > At 4800b each character takes 1/600th of a second and the GPS > may spend 1/2 second sending text each second, > Maybe for casual use you don't care? Half a second off is OK. > Or you could substract a fudge factor of 1/4 second from what > the GPS tells you. But some people do want precise > time at the micro or nano second level. > > Some GPSes allow you to control the order of which lines come > out first. Just make it so the time comes out first if it > doesn't aleady and maybe this is good enough. Some GPSes can > do 9600 baud. So the delay is cut in half > Yes, I get your point. However, am I right in saying that, although there is a delay from the actual tick to the time the time is emitted, this delay is more or less fixed & non cumulative? If so, then it will serve my purpose as a clock showing the time of the day with a resolution of 1 sec. Also, from my short research, most GPS receivers emit a 1 Hz pulse which is 'spot on' and may be used to calibrate any delay/error...right? I've shortlisted Trimble/Lassen iQ, Garmin GPS18 LVC & Motorola FS Oncore GPS modules, but I would welcome any suggesations. Thanks, --Royce. -- Using Opera's revolutionary e-mail client: http://www.opera.com/mail/ _______________________________________________ AVR-chat mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/avr-chat
